+ spin_lock(&elv_list_lock);
+
+ list_for_each_entry(e, &elv_list, list) {
+ if (elv_support_features(e->elevator_features,
+ q->required_elevator_features))
+ break;
+ }
+
+ if (e && !try_module_get(e->elevator_owner))
+ e = NULL;
+
+ spin_unlock(&elv_list_lock);
+
+ return e;
+}
+
+/*
+ * For a device queue that has no required features, use the default elevator
+ * settings. Otherwise, use the first elevator available matching the required
+ * features. If no suitable elevator is find or if the chosen elevator
+ * initialization fails, fall back to the "none" elevator (no elevator).
+ */
+void elevator_init_mq(struct request_queue *q)
+{
+ struct elevator_type *e;
+ int err;
+
+ if (!elv_support_iosched(q))
+ return;
+
+ WARN_ON_ONCE(test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags));